Abstract: A digital pulse width modulation(DPWM) controller was researched and designed based on field programmable gate array(FPGA).And a new method was also presented to produce PWM driving signals in all-digital inverter.The real-time counting comparative method was introduced to realize high frequency PWM signals with adjustable frequency and duty cycle, which can realize that every moment of the PWM signals is knowable and controllable.Every block of the controller was described in detail after analysis of principles and parameters of the DPWM controller.The digital anti-jamming technology was adopted to make the system work steadily in the terrible environment with strong disturbance, high voltage and large current.The simulation and actual welding experiments demonstrate that the high-speed DPWM controller can run steadily and reliably in a long time and be widely used in the digital welding machines.